ABSTRACT Behavioral parent training (BPT) is well-established for treating Attention Deficit Hyperactivity Disorder and associated impairments, but short-term treatment gains for children typically lack generalizability and sustainability. Lack of parental adherence contributes to these limited effects, since BPT relies on parents using treatment-recommended parenting skills with children in daily life contexts. A number of barriers can impede parent adherence including skill competence, executive functioning (EF) processes, and motivation/ attitudes, as well as maintenance-specific barriers after in-person treatment ends (e.g. competence adapting skills to new challenges; EF/motivational barriers from lack of ongoing social support). Such barriers may be directly addressable through innovative dHealth tools. The objective of this study is to develop and test a novel and scalable digital health solution designed to address barriers and improve parent skill utilization in daily life contexts, the hypothesized mechanism of action for BPT, with the goal of improving sustainability of treatment outcomes for youth with ADHD. A dHealth tool will be fully developed to augment group-based BPT in school settings, maximizing accessibility of the treatment. Aim 1 is to develop a technology-enhanced version of behavioral parent training for improving parent adherence and collect preliminary data on usability, feasibility and acceptability. Qualitative and quantitative input from key stakeholders (parents, children and clinicians) through focus groups, qualitative interviews and extended formative usage testing will be obtained. The tool addresses barriers to skill utilization with specific features: 1) skill competence: skills library/videos, knowledge questions, tailored content, and interactive troubleshooting wizard, 2) EF processes: in vivo notifications for skill use/coaching, linked parent/child views of interactive/personalized plans integrated in daily routines with child involvement, streamlined content, 3) motivation/attitudes: motivational/ ?change talk? messaging, goal- setting, automated monitoring of parent/child progress, gamification, and digital rewards, 4) maintenance- specific barriers: individualized troubleshooting to assist with new problems and social features to support parents after in-person treatment ends. Aim 2 is to implement a pilot RCT of the technology-enhanced version of BPT (N=30) compared to BPT only (N=30) to gather preliminary efficacy data on immediate and sustained (up to 12 months after treatment) parent skill utilization (primary target), and parenting barriers (intermediate targets) to inform a larger scale trial. Aim 3 is to examine whether parent skill utilization (target mechanism) is engaged by the app and whether this engagement is associated with improved child outcomes. We will explore the association between: (a) app use and skill utilization; (b) skill utilization and child outcomes, and c) app use with reduced parent barriers for predicting skill utilization and child outcomes. Exploratory analyses examine the potential mediating mechanism of skill utilization (immediate and sustained) for optimizing the association between the dHealth tool and improved child and parenting outcomes.